Background information and definitions
Hedgerows provide important semi-natural habitat within farmland, offering food and shelter in their own right, as well as connectivity between other patches of semi-natural habitat, such as woodland. Hedgerows also reduce the temperature fluctuations experienced in open farmland, which may facilitate greater species survival or movement through the landscape. The presence of hedgerows in an agricultural landscape has been found to increase both the abundance and species richness of butterflies recorded (Luppi et al. 2018), therefore planting new hedgerows may help butterfly and moth populations on farmland to recover.
For studies on managing existing hedgerows, see “Manage hedgerows to benefit wildlife (e.g. no spray, gap-filling and laying)”.
Luppi M., Dondina O., Orioli V. & Bani L. (2018) Local and landscape drivers of butterfly richness and abundance in a human-dominated area. Agriculture, Ecosystems & Environment, 254, 138–148.
Supporting evidence from individual studies
A replicated, site comparison study in 1987–1988 and 1997 on two arable farms in England, UK (Dover et al. 2000) found that hedgerows did not have a higher abundance or species richness of butterflies than grass banks between fields. At one farm in 1987–1988, the abundance and species richness of butterflies was similar along hedgerows (abundance: 9–12 butterflies/100 m; richness: 11–13 species) and grass banks (abundance: 5–8 butterflies/100 m; richness: 7–9 species). In 1997, at a second farm, the abundance and species richness of butterflies was similar along hedgerows (abundance: 10 butterflies/100 m; richness: 1.5 species) and grass banks (abundance: 6 butterflies/100 m; richness: 1.1 species). At a farm in Hampshire, from May–September, butterflies were surveyed 13 times along four hedgerows and three grass banks in 1987, and 10 times along eight hedgerows and four grass banks in 1988. At a farm in Cheshire, from July–August 1997, butterflies were surveyed five times along 16 hedgerows and 12 grass banks.Study and other actions tested
A replicated, paired, site comparison study in 1999 on five farms in the UK (Thomas et al. 2000) found that the abundance and species richness of butterflies was higher along hedgerows than on beetle banks established in the centre of fields. Along hedgerows both the abundance (2–6 individuals/transect) and species richness (1–3 species/transect) of adult butterflies were higher than on beetle banks (abundance: 1–2 individuals/transect; richness: 0.5–2 species/transect). A total of 19 species from four families were recorded along hedgerows, compared to 12 species from three families on beetle banks. Adult butterflies were recorded on 82 transects along hedgerows and beetle banks on five farms in June, July and August 1999.Study and other actions tested
A replicated study in 1996–1999 on semi-upland farmland in mid-Wales, UK (Hayes et al. 2001) found that seven species planted in two hedgerows supported different numbers of arthropods, including moths and butterflies. The number of arthropods (e.g. insects) recorded differed between hedgerow species: common gorse Ulex europaeus (1,007 arthropods), sessile oak Quercus petraea (436), blackthorn Prunus spinosa (381), hawthorn Crataegus monogyna (258), silver birch Betula pendula (180), rowan Sorbus aucuparia (110) and ling heather Calluna vulgaris (53). Sessile oak supported the most diverse group in terms of arthropod orders, with 13 out of 15 orders recorded, two of which were not found on any other plant species. Hawthorn and common gorse were the next most diverse, each with one unique arthropod order. Common gorse, sessile oak, blackthorn and rowan between them had representatives of all 27 families of moths and butterflies (Lepidoptera), beetles (Coleoptera) and true bugs (Hemiptera) recorded in the study. Planting was undertaken in 1996 within the fenced (2 m wide) margins of two fields. Margins were divided into eight 6-m plots, which were planted with a double row of 30–40 plants of each species, replicated across three blocks. Arthropods were sampled by tree beating at five points/plot in June, August and September 1998–1999.Study and other actions tested
Referenced paperHayes M.J., Jones A.T., Sackville Hamilton N.R., Wildig J. & Buse A. (2001) Studies on the restoration of Welsh Hedges. Pages 339-348 in: C. Barr & S. Petit (eds.) Hedgerows of the World: Their Ecological Functions in Different Landscapes: 10th Annual Conference of the International Association for Landscape Ecology. International Association for Landscape Ecology, Birmingham, UK.
A paired, site comparison study in 2002 on one arable and one livestock farm in Ireland (Bracken 2004) reported that a higher abundance and species richness of butterflies was found along hedgerows than in field interiors. Results were not tested for statistical significance. On one farm, 13 butterflies of 7 species were recorded along a hedgerow transect next to arable fields, compared to 2 butterflies of 2 species in an arable field interior. On the other farm, 6 butterflies of 3 species were recorded along a hedgerow transect next to pasture fields, compared to 0 butterflies in a pasture field interior. From April–September 2002, one arable farm was surveyed seven times, and one livestock farm with improved grassland was surveyed 10 times. Butterflies were surveyed along four 250-m transects, one along a hedgerow and one through a field interior on each farm.Study and other actions tested
A replicated, controlled study in 1996–2000 on three arable farms in Essex, UK (Field & Mason 2005) found that gatekeepers Pyronia tithonus were more abundant on grass margins and cropped field edges next to hedgerows than on grass margins without hedgerows. Gatekeepers were more abundant on sown grass margins next to hedgerows (11.9 individuals/km) and on cropped field edges with hedgerows (0.7–17.3 individuals/km) than on sown grass margins without hedgerows (0.2 individuals/km). Eleven grass margins (2 m wide, 141–762 m long) were established in October 1996–2000 by sowing one of three seed mixtures containing 4–6 grass species next to 100–467 m of existing hedgerow. Two grass margins (2 m wide, 285 m long) were established on field edges without hedgerows. Three further field edges without margins (one on each farm, 133–343 m long) had 100–300 m of existing hedgerow. Gatekeeper abundance was monitored weekly along each grass margin and cropped edge in July and August 1997–2000.Study and other actions tested
A replicated, paired, site comparison study in 2001 on 16 arable farms in Ontario, Canada (Boutin et al. 2011) found that woody hedgerows supported a higher abundance and species richness of macro-moths than crop fields. Along hedgerows, both the total abundance (80–418 individuals/trap) and species richness (13–26 species/trap) of moths were higher than in the centre of crop fields (abundance: 40–135 individuals/trap; richness: 8–17 species/trap). Of 126 species collected only once, 78 were found along hedgerows compared to 48 in crop fields (statistical significance not assessed). See paper for species results. Sixteen woody hedgerows (184–203 m long, 10–16 m wide, 18–21 m tall) and their adjacent arable fields were selected on eight organic farms (no chemical inputs for ≥3 years) and eight conventional farms (chemical fertilizers and herbicides applied). Hedgerows were trimmed when too wide, and dead trees were removed. From June–September 2001, macro-moths were sampled on six nights/site. Each night, one fluorescent UV black-light funnel trap was set halfway along a hedge, and one was set ~50 m away in the middle of the adjacent crop field. Two organic and two conventional farms were sampled each night, and all sites were sampled within five nights every two weeks.Study and other actions tested
A site comparison study in 2011–2013 on a mixed farm in Northamptonshire, UK (Coulthard et al. 2016) found that the abundance of moths was higher close to hedgerows than further away. The number of moths recorded 1 m from a hedgerow (225 individuals) was higher than the number recorded 5 m (73 individuals) or 10 m (34 individuals) away. Moths observed 1 m from a hedge were more likely to be moving along it (156 individuals) than at right angles (13 individuals) or diagonal (19 individuals) to it, whereas this was not the case for moths recorded 5 or 10 m from the hedge (5 m: along = 30, right angle = 18, diagonal = 11 individuals; 10 m: along = 9, right angle = 11, diagonal = 10 individuals). Across a 600-ha predominantly arable farm, most hedgerows were cut and not laid, but the condition varied from thick and managed to gappy and derelict. On warm nights (>5°C) between May and July 2011–2013, moths were observed for 15 minutes at each of 1, 5 and 10 m away from 13 different hedgerows. The number of moths, and the direction of flight of each individual, was recorded.Study and other actions tested